Table 1.

Quantitative summary of the literature search process.

Bibliographic repositories	N	n	Spreadsheets in InvaCost_references*
Web of Science	16.875	1.333	WoS-collected_refs; WoS-screened_refs
Google Scholar	992	310	GS-collected_refs; GS-screened_refs
Google search engine	361	119	Go-collected_refs; Go-screened_refs
Targeted collection	1.917	634	TC-collected_refs; TC-screened_refs; Cited references

Search was performed using four bibliographic repositories. N: the number of references initially collected after applying specific search strings (Web of Science, Google Scholar, Google search engine) or as the result of targeted collection. n: the number of relevant materials (i.e. materials expected to contain cost estimates based on the contents of titles, abstracts and keywords) derived from N. The figures for the targeted collection include 484 references gathered within the analysed relevant materials. *The spreadsheets in which all details of associated references were recorded³⁰ are also referenced.